U.S. Secretary of State Hillary Clinton warned in Doha on Monday that Iran is "moving toward a military dictatorship," saying top posts in the country are being "supplanted."

Speaking to students of Qatar's branch of Carnegie-Mellon University, Clinton said Washington is open to "engagement" with Iran, but, at the same time, it will not stand hand-folded towards its pursuit of a threatening nuclear program.

"We are planning to try to bring the world community together in applying pressure to Iran through sanctions adopted by the United Nations that will be particularly aimed at those enterprises controlled by the Revolutionary Guard which we believe, in effect, supplanting the government of Iran," she said in remarks posted on the website of the U.S. Department of State.

"We see that the government of Iran, the supreme leader, the president, the parliament, is being supplanted, and that Iran is moving towards a military dictatorship. Now, that is our view," Clinton said.

What Washington is trying to do is to send a message to Iran that "we still would be open to engagement, we still believe there is a different path for Iran to take," she said.

But, the world should be united in sending unequivocal message that "we will not stand idly while you pursue a nuclear program that can be used to threaten your neighbors, end even beyond."

Questioned if, by saying so, she indicates that there is no plan to attack Iran, Clinton said that Washington is interested in changing Iran's behavior.

"We have pursued dual track, not a triple track, but a dual- track approach of engagement and potential pressure and that is what we're focused on," she said.

Clinton also criticized Tehran over reluctance to cooperate with the international community and violations of its obligations under the Non-Proliferation Treaty and other United Nations resolutions.

"We see Iran being exposed for having a secret facility at Qom, We see Iran refusing an offer from Russia, the United States, and France to help it get the enriched uranium ... We see the president of Iran ordering the nuclear program to do its own enriching, and to begin to move toward the level of enrichment that certainly is troubling to us, because of what it well could be, with respect to nuclear weapons," she said.

She also voiced concern over Iranian regime's treatment of the opposition in the country.

"We are deeply concerned about the way Iran is treating its own people, and the way it has executed demonstrators, imprisoned hundreds and hundreds of people whose only offense was peacefully protesting the outcome of the elections," she added.

Clinton arrived in Qatar on Sunday as part of her Gulf tour which includes Saudi Arabia, where she is due to meet with King Abdullah bin Abdul-Aziz and Foreign Minister Saud al-Faisal.